I have both books (each now over 20 years old), but I think "Casting the Net" is a slightly more rigorous and somewhat less "journalisty" history with a better collection of diagrams and scribbles by the key figures involved.
Again, and already mentioned, "The Soul of a New Machine" by Tracy Kidder is a great read. It's a particular favourite what with being an ex-Data General field engineer (maintained and fixed Nova 3/4 and Eclipse S/130/140's and associated peripherals).
I can also recommend "In Search of Stupidity:Over 20 Years of High-Tech Marketing Disasters" which about how the old giants of the early PC software industry (Ashton Tate, MicroPro et al) made colossal mistakes resulting in their extinction.
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